The invention relates to the making of tobacco streams (hereinafter called tobacco filler streams or filler streams) which are to be transformed into rod-like fillers for the production of cigarettes, cigarillos, cigars, cheroots and analogous rod-shaped smokers' products. More particularly, the invention relates to improvements in methods of and in apparatus for simultaneously making a plurality of tobacco filler streams.
It is already known to simultaneously produce two tobacco filler streams by dividing a single layer of tobacco particles into two narrower layers each of which is converted into a discrete filler stream. As a rule, the single layer is advanced along a concave path in a direction from a station where particles of tobacco are gathered into the single layer toward two endless foraminous belt conveyors each of which accepts one of the narrower layers and converts it into a filler stream. The filler streams are then ready to be transformed into rod-like fillers, normally by removing therefrom surpluses of tobacco particles. The fillers are thereupon draped into webs of cigarette paper or other suitable wrapping material to form with the draped webs continuous rods which are ready to be subdivided into rod-shaped smokers' products of unit length or multiple unit length.
The belt conveyors normally advance the respective filler streams at right angles to the direction of advancement of narrower layers toward the converting stations. Reference may be had, for example, to commonly owned U.S. Pat. No. 4,889,138 describing an apparatus wherein a single concave surface for the single tobacco layer is followed by two narrower surfaces each of which receives and guides one of the two narrower layers toward the respective foraminous belt conveyor. A drawback of the apparatus which is described in U.S. Pat. No. 4,889,138 is that it must be equipped with rather complex, expensive and bulky means for ensuring that the quality of one of the two tobacco filler streams will match or at least closely approximate the quality of the other filler stream. The most important criteria of tobacco filler streams are the weight of each unit length of filler stream, the density, the hardness and particularly the homogeneousness, i.e., the extent to which various types of tobacco particles are intermixed in successive increments of each filler stream. Each filler stream normally contains several types or brands of tobacco, such as Virginia, Burley and Oriental, short and long shreds, particles of tobacco leaf laminate and fragments of tobacco ribs and/or particles of natural tobacco, reconstituted tobacco and substitute tobacco. It is desirable to ensure that each and every unit length of each of a plurality of simultaneously produced filler streams will contain identical quantities of all ingredients or constituents because even minor departures from homogeneousness of the mixture can greatly affect the taste and/or other desirable characteristics of rod-shaped smokers' products.